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December 2014 Topographic Data Release Notes

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This release comprises 61 ‘HighVis’* and 22 selected updates; a total of 83 Topo50 sheets updated.

*HighVis (high visibility approach) - ie where they are present, new roads (and road names), backcountry tracks & huts, schools and transmission line features are checked and updated. Changes to gazetted geographic names are also made. For the remaining features, each sheet is scanned, and only features that stand out as being significantly different from the previous edition are updated.

On CA11 Aspiring Pass, Quarterdeck Pass text has been moved to be closer to the actual feature and BX24 Christchurch has had the earthquake affected areas (CBD and urban) adjusted.

Many of the updates in the central North Island comprise of changes from forestry to lifestyle blocks, and include the mapping of several power facilities.

Topo50 Gridless released

In the last release “Gridless” versions of the raster map images of Topo250, Tokelau, Niue and Cook Islands raster map layers were published; Topo50 gridless versions have now also been generated and published on the LINZ Data Service website.

Schema changes

The new rna_sufi attribute provides a new set of ID values and replaces the old name_id attribute. A CSV file that maps the link between the old and new ID values is provided on the LINZ Data Service.

Topo50 Feature ID’s added to the LINZ Data Service (LDS) Topo50 data

A new attribute containing a Topo50 Feature ID, t50_fid, on Topo50 data downloaded from the LDS. The Topo50 Feature ID is not available from data downloaded from the Map Chooser.

The Topo50 Feature ID is a unique identifier for use on Topo50 data, but is not a universal ID. The intention is to manage Topo50 Feature ID’s as persistent, however this is not guaranteed and there will be instances where what appears to be a minor change to a feature may result in a new Topo50 Feature ID being assigned.

To enable more agile updating within LINZ, Topo50 data has been tiled to the Topo50 map sheet layout. Previously all features except contours were tiled to the Topo250 map sheets; Topo50 contours have always been tiled to Topo50 map sheets.

This change will not be highly visible to LDS users as prior to loading onto the LDS an edge-matching process has been run to re-join all line and polygon features.

However the process has identified a number of edge-match issues which are planned to be corrected, where possible, in the next few data releases.

As point features are not merged across map sheets, Geographic Name point features representing an area crossing a map sheet edge may be depicted with multiple points with different ID’s.

LDS Topo50 line and polygon features that have been joined across map sheet edges have been assigned with a Topo50 Feature ID generated from a sequence above 100,000,000.

Topographic Data Dictionary changes

Nil; however a future update is proposed to include documentation of the Topo50 Feature ID, the new attribute rna_sufi, and other minor changes.